Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01G—WEIGHING
  • G01G19/00—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups
  • G01G19/40—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups with provisions for indicating, recording, or computing price or other quantities dependent on the weight
  • G01G19/413—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups with provisions for indicating, recording, or computing price or other quantities dependent on the weight using electromechanical or electronic computing means
  • G01G19/414—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups with provisions for indicating, recording, or computing price or other quantities dependent on the weight using electromechanical or electronic computing means using electronic computing means only
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
  • B60R21/00—Arrangements or fittings on vehicles for protecting or preventing injuries to occupants or pedestrians in case of accidents or other traffic risks
  • B60R21/01—Electrical circuits for triggering passive safety arrangements, e.g. airbags, safety belt tighteners, in case of vehicle accidents or impending vehicle accidents
  • B60R21/015—Electrical circuits for triggering passive safety arrangements, e.g. airbags, safety belt tighteners, in case of vehicle accidents or impending vehicle accidents including means for detecting the presence or position of passengers, passenger seats or child seats, and the related safety parameters therefor, e.g. speed or timing of airbag inflation in relation to occupant position or seat belt use
  • B60R21/01512—Passenger detection systems
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01G—WEIGHING
  • G01G19/00—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups
  • G01G19/40—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups with provisions for indicating, recording, or computing price or other quantities dependent on the weight
  • G01G19/413—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups with provisions for indicating, recording, or computing price or other quantities dependent on the weight using electromechanical or electronic computing means
  • G01G19/414—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups with provisions for indicating, recording, or computing price or other quantities dependent on the weight using electromechanical or electronic computing means using electronic computing means only
  • G01G19/4142—Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups with provisions for indicating, recording, or computing price or other quantities dependent on the weight using electromechanical or electronic computing means using electronic computing means only for controlling activation of safety devices, e.g. airbag systems

Definitions

• This invention relates to a method and apparatus for measuring seat occupant weight and eliminating error caused by over tightened seat belts to improve airbag deployment control. Specifically, a compensation factor is determined based on seat occupant weight to correct error caused by an over-tight seat belt used to secure a child seat to a vehicle seat.
• the combined output from the mats or the sensors is used to determine the weight of the seat occupant.
• These current sensor systems can have difficulty determining whether an adult is belted to the seat or whether a child car seat is belted to the seat.
• an excess force acts on the sensors mounted within the rear portion of the seat, which interferes with accurate sensing of the weight of an occupant.
• Overtightening of the seatbelt which makes it pull down on the rear of the seat, causes this force.
• the increased force causes the system to incorrectly detect a large child or small adult in the seat as opposed to a small child, resulting in airbag deployment instead of airbag suppression.
• the current weight sensing systems have difficulty in discerning between an adult occupant and a child in a child seat.
• the subject invention provides a method and apparatus to compensate for loads induced by seat belt tension acting on a child seat or other similar occupant securely belted to a vehicle seat. Using the total measured occupant weight and the distribution of that weight on the vehicle seat, a compensation factor is generated for the belt- induced load.
• the compensation factor provides a reliable method of differentiating between a child seat with a large belt force and a small adult, thus resulting in proper airbag deployment control.
• the method for correcting seat occupant weight measurement error induced by a seat belt includes the following steps.
• the seat occupant weight is measured and an asymmetry load is determined.
• the asymmetry load is the load that is applied to a vehicle seat based on a tension force generated by securing the occupant to the seat with a seat belt.
• a compensation factor is generated if the asymmetry load is greater than a minimum threshold and then the seat occupant weight is modified by the compensation factor.
• the compensation factor is only generated if the weight is less than a predetermined weight.
• An airbag control signal is used to modify airbag deployment based on the corrected occupant weight
• the method differentiates between a child seat belted to the vehicle seat and a small adult.
• a seat occupant weight signal is generated representing the total measured weight of the child and child seat.
• An asymmetry load is determined based on the sensor and seat belt mounting locations. If the asymmetry load is above a predetermined minimum and if the occupant weight signal is less than a predetermined weight then the compensation factor is generated and the occupant weight signal is modified. The child seat is detected if the modified weight signal is less than a predetermined threshold and airbag deployment is suppressed if the child seat is detected.
• the system for correcting seat occupant weight measurement error induced by a seat belt includes a vehicle seat having a seat back supported with respect to a seat bottom and a sensor assembly for measuring the weight of a seat occupant to generate a total measured seat occupant weight signal.
• a seat belt assembly secures the seat occupant to the vehicle seat and includes at least one seat belt mounting portion positioned adjacent to the vehicle seat for mounting the seat belt assembly to a vehicle structure.
• a control unit generates an asymmetry load based on the position of the seat belt mounting portion and the measured weight of the seat occupant and provides a compensation factor when the asymmetry loads exceeds a predetermined threshold.
• the compensation factor modifies the total measured seat occupant weight signal to correct weight measurement error induced by seat belt tension forces applied to the occupant.
• the control unit detects a child seat when the modified signal is less than a predetermined limit and sends a control signal to an airbag controller to suppress airbag deployment.
• the subject invention provides a simple, reliable, and accurate method and apparatus for differentiating between various types of seat occupants.
• Figure 1 is a schematic view showing a vehicle with a seat belt assembly and an airbag system with an occupant sitting in a seat showing the airbag in an active state in dashed lines.
• Figure 2 is a side view of a seat assembly with an infant car seat secured to the vehicle seat with a seat belt.
• Figure 3 is a side schematic view of seat belt forces applied to a seat assembly
• Figure 4 is an alternate embodiment of the anchor of Figure 3.
• Figure 5 is a graph of Compensation Percent vs. Asymmetry Percentage.
• Figure 6 is a graph of Compensation Percent vs. Measured Weight.
• a vehicle is shown generally at 10 in Figure 1 with an adult occupant 12 seated in a seat having a seat back 14 supported with respect to a seat bottom 16.
• the vehicle 10 is equipped with an occupant restraint system that includes an airbag system 18 and a seatbelt system 20 that are used to restrain occupants 12 within the vehicle 10 under certain predetermined deceleration requirements. If the vehicle decelerates suddenly, such as when a collision occurs, occupants 12 will tend to continue to move forward due to inertial effects.
• An airbag controller 22 deploys an airbag 24 under predetermined collision circumstances to decelerate the occupants' impact speed before they contact a vehicle structure, such as a steering wheel or dashboard 26.
• the airbag system 14 deploys an airbag 24 under certain collision conditions.
• the deployment force for the airbag 24, shown in dashed lines in Figure 1, varies depending upon the type of occupant that is belted to the seat 12.
• the airbag 24 should be deployed in a normal manner shown in Figure 1. If there is an infant or child seat 28 secured to the vehicle seat 12, see Figure 2, then the airbag 24 should not be deployed.
• One way to determine this is by monitoring the weight exerted on the seat.
• the subject invention provides a method to compensate for loads induced by seat belt tension acting on the child seat 28.
• a compensation factor for the belt-induced load can be determined.
• airbag deployment is suppressed, i.e., turned off, for occupants (children and child seats) that weigh less than fifty- five (55) pounds.
• the airbag 24 is turned on for occupants that weigh more than one hundred and five (105) pounds.
• the airbag 24 can be deployed at full force or some lesser deployment force for occupants that are greater than fifty-five pounds. While fifty-five pounds is a preferred limit, other weight limits could also be used.
• the subject invention corrects for this error by determining the percentage of measured load induced by the occupant and the amount of the measured load induced by the seat belt 20.
• At least one seat belt mounting portion 30 is generally located aft and to one side of the seat, see Figure 3.
• the mounting portion 30 is used to secure the seat belt 20 to a vehicle structure such as the pillar, seat structure, or floor 32, for example.
• the load Ft induced by the seat belt 20 not only has a vertical component Ftv, but also has a horizontal component Fth.
• the resulting force vector Ft causes an asymmetry in the seat loading that is detected by a seat weight measuring system.
• the seat weight measuring system preferably includes a sensor assembly 34 comprised of a plurality of load cells 36 that are mounted within the seat bottom 16.
• the sensor assembly 34 includes four (4) load cells 36.
• a first load cell 36a is positioned near a left front portion 38 of the seat
• a second load cell 36b is positioned near a left rear portion 40 of the seat
• a third load cell 36c is positioned near a right rear portion 42 of the seat
• a fourth load cell 36d is positioned near a right front portion 44 of the seat.
• Each of the four load cells 36a, 36b, 36c, 36d generates a weight measurement for the left front (LF), left rear (LR), right rear (RR), and right front (RF) portions of the seat respectively. These measurements are combined to generate a total measured occupant weight signal 46, which is transmitted to a control unit 48, or other central computer or processing unit. The control unit 48 then generates a control signal 50 that is transmitted to the airbag controller 22 to control deployment of the airbag 24.
• the seat belt mounting portion 30 is mounted aft of the right rear (RR) portion 42 of the seat.
• An optional mounting portion 52 is shown aft of the left rear (LR) portion 40 of the seat and is shown in dashed lines.
• the seat belt force Ft is a resultant vector with horizontal Fth and vertical Ftv components. This vector force Ft causes an asymmetry in the seat loading, which is detected by the load cells 36. This asymmetry can be calculated from the four individual load measurements and used to calculate a compensation factor to correct for the additional belt load. The asymmetry direction is based on the load cell 36 and seat belt mounting locations 30.
• the asymmetry derived from these equations is processed by the control unit 48 to generate a compensation factor that is a percentage of the total weight measured for the seat occupant.
• a transfer function monitors the asymmetry.
• the compensation factor is not generated until the asymmetry reaches a minimum lower threshold, shown in Figure 5.
• Figure 5 depicts a graph of the Percent of Compensations vs. the Percent of Asymmetry. There is no compensation until the asymmetry reaches a belt tension compensation lower limit (BTC LOW LIMIT). Once this minimum threshold is achieved, the compensation factor is set to a belt tension compensation minimum (BTC COMP MEN) or initial value. As the asymmetry increases, the compensation factor increases until a maximum belt tension compensation value (BTC COMP MAX) is reached.
• This maximum compensation factor corresponds to a maximum asymmetry limit at a belt tension compensation high limit (BTC HIGH LIMIT).
• BTC HIGH LIMIT belt tension compensation high limit
• the initial stop band shown on the graph for the compensation factor allows for extreme seating positions with large children and small adults.
• the maximum compensation factor is used to limit the compensation to a realistic value.
• seat belt induced loads are not an issue for adults.
• the seat belt 20 will become very uncomfortable for the occupant before the additional load causes any error. Therefore, the compensation needs to be turned off for adult occupants and left on for children.
• the transition from compensation to no compensation is based on total measured weight. For occupants below a predetermined lower measured weight, the compensation correction is on, and for occupants above a predetermined upper measured weight, the compensation correction is off. A scaling zone between these two weight limits helps to smooth transition.
• the graph shown in Figure 6 shows the Percent Compensation vs. Measured Weight. At measured weights below a minimum belt tension compensation limit (BTC ON LIMIT), there is one hundred percent compensation. At measured weights above an upper belt tension compensation limit (BTC OFF LIMIT) there is zero percent compensation. At measured weights between these two limits, the compensation factor is scaled and decreases as the measured weight approaches the upper limit. The scaled compensation factor is then multiplied by the total measure weight and the resulting weight is subtracted from the total measured weight to provide a modified weight. The modified weight is more accurate than the originally measured total weight because the compensation factor has been applied to eliminate loading induced by the seat belt 20. Thus, the difference between small adults and a child in a child seat 28 is easily distinguished.
• the subject sensing system provides simplified and efficient apparatus and method for determining whether conditions are proper for deploying an airbag 24 by correcting seat occupant weight measurements by compensating for seat belt induced loading to detect whether a child seat 28 or an adult 12 is belted to the seat.
• the system provides reliable and accurate measurements.

Landscapes

• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Mathematical Physics (AREA)
• Theoretical Computer Science (AREA)
• General Physics & Mathematics (AREA)
• Mechanical Engineering (AREA)
• Air Bags (AREA)
• Seats For Vehicles (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

Family

ID=22547186

Family Applications (1)

Country Status (6)

Cited By (6)

Families Citing this family (15)

Citations (4)

Family Cites Families (9)

• 2000
  • 2000-08-29 KR KR1020027002912A patent/KR20020029778A/ko not_active Application Discontinuation
  • 2000-08-29 WO PCT/US2000/023682 patent/WO2001018507A1/en not_active Application Discontinuation
  • 2000-08-29 EP EP00959549A patent/EP1210569B1/de not_active Expired - Lifetime
  • 2000-08-29 JP JP2001522048A patent/JP2003508776A/ja not_active Ceased
  • 2000-08-29 DE DE60004536T patent/DE60004536T2/de not_active Expired - Lifetime
  • 2000-08-29 US US09/650,349 patent/US6536797B1/en not_active Expired - Fee Related

Patent Citations (4)

Also Published As

Similar Documents

Legal Events